JP2008001965A - Method for producing porous body and method for producing porous resin body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a porous body where a porous body in which many pores are formed can be inexpensively produced. <P>SOLUTION: The production method comprises: a discontinuous film formation stage where discontinuous films 2 are formed on the surface 1a of an Si base material 1 having <110> crystal orientation; and an anisotropic etching stage where, with the discontinuous films 2 as masks, the surface 1a of the base material 1 is subjected to anisotropic etching by wet etching using an NaOH aqueous solution, a KOH aqueous solution or a TMAH aqueous solution, so as to obtain a porous body 6 in which many holes 5 are formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a porous body, and more particularly to a method for producing a porous body used as a porous membrane in the water treatment field, the medical field, the food industry field, the battery field and the like. Moreover, this invention relates to the method of manufacturing a porous resin body using the porous body manufactured by this manufacturing method.

  In recent years, porous membranes have been used in various fields such as water treatment fields, medical fields such as blood purification, food industry fields, battery separators, charged membranes, and fuel cells. As a result, the structure and functions of the porous membrane itself have been diversified. Among such porous membranes, there is a porous membrane called a track etch membrane having through-holes with uniform pore diameters that has a special shape and function.

  The characteristics of the track etch membrane include that the pore size distribution is very sharp, that particles larger than the pore size are trapped on the membrane surface, and that the filtering ability is high, and the trapped material can be easily observed. In addition, recently, plating using a track etch membrane as a template has been applied to the production of various metal nanotubes and nanowires.

  Disadvantages of the track etch membrane include that the film thickness cannot be increased and that the orientation of the through holes is different. These are due to the electron beam irradiation or heavy ion irradiation steps in the manufacturing process, and their improvement is very difficult.

  As a film having a through-hole such as a track etch membrane, there is a resist film for semiconductor manufacturing, or a film patterned by lithography, nanoimprinting, or the like on Si, ceramics, metal, or the like. Since these films are manufactured by applying lithography technology, within the mask manufacturing technology, not only those having various hole shapes, but films having various structures such as trenches, Films with regularly arranged holes can also be produced. In addition, it has become possible to manufacture a minimum processing dimension as small as several tens of nanometers. Recently, along with technological advancement in the MEMS field, it has become possible to manufacture through holes having a high aspect ratio with an aspect ratio of several tens or more.

  However, when a porous film such as a track etch membrane is manufactured by the above-described technique, it is expensive to manufacture a mask in common, and the manufacturing cost of the porous film is increased. There is.

  The present invention has been made in view of such problems of the prior art, and it is a first object of the present invention to provide a method for producing a porous body that can inexpensively produce a porous body having a large number of pores. 1 purpose.

  In addition, a second object of the present invention is to provide a method for producing a porous resin body that can produce a porous resin body having a large number of pores at low cost.

  As a result of intensive studies, the present inventors have obtained the following knowledge. That is, when a metal film is formed on a substrate such as Si by a film formation method such as sputtering, the film is a discontinuous film at the initial stage of film formation, and is in an island shape or a state where holes are opened in places. It has been found that if the substrate is etched using this discontinuous film as a mask, it is not a regularly arranged or shaped hole, but a straight hole can be formed at low cost, whereby a porous body can be produced.

  That is, according to the first aspect of the present invention, there is provided a method for producing a porous body that can inexpensively produce a porous body in which a large number of pores are formed. According to this method, a discontinuous film is formed on the surface of the substrate (discontinuous film forming step). Using the discontinuous film as a mask, the surface of the substrate is anisotropically etched to obtain a porous body in which a large number of pores are formed (anisotropic etching step).

  According to the above-described method, a porous body having fine straight holes can be manufactured at low cost by anisotropically etching the base material using a discontinuous film that can be formed at low cost as a mask. That is, a mask corresponding to a wide pore size of a straight hole can be formed at low cost from a relatively large pore size of micron order or larger to a very fine pore size of nano order such as 0.5 to 100 nm. Therefore, a porous body having a direct hole of these sizes can be manufactured at low cost.

  In the discontinuous film forming step, an irregular discontinuous film may be formed, or the discontinuous film may be formed by sputtering, CVD, or vapor deposition. Further, in the discontinuous film forming step, a non-conforming layer made of Cu, Ru, Co, Ta, Ti, W, Fe, Ni, Au, Ag, Pb, TaN, TiN, WN, WNC, polyethylene, fluororesin, or polyimide. A continuous film may be formed. Furthermore, the discontinuous film used as the mask may be removed after the anisotropic etching process (discontinuous film removing process). Further, after the discontinuous film forming step, the discontinuous film may be subjected to annealing treatment or laser irradiation treatment.

  According to the 2nd aspect of this invention, the manufacturing method of the porous body which can manufacture the porous body in which many holes were formed at low cost is provided. According to this method, the porous material having continuous pores is formed on the surface of the substrate (porous material forming step). Using the porous material as a mask, the surface of the substrate is anisotropically etched to obtain a porous body in which a large number of holes are formed (anisotropic etching step).

  Various methods and materials have been conventionally considered as a method for producing a porous material having continuous pores, and there are very various options. Therefore, an optimum porous material can be selected from various options and used as a mask according to various demands such as a base material, an anisotropic etching method, and a desired pore size. Therefore, according to the above-described method, the production cost of the mask is reduced, and further, the material and pore size of the mask can be selected from various options, and the porous body having fine pores with a wide pore size can be selected at a low cost. Can be manufactured.

  In the porous material forming step, a porous material having irregular continuous pores may be formed. Further, the porous material can be formed by a phase separation method, a sintering method, or an anodic oxidation method. Furthermore, a porous material made of polyethylene, polyimide, alumina, titanium oxide, or SiC can be used. Furthermore, after the anisotropic etching step, the porous material used as the mask may be removed (porous material removing step).

  Here, the base material is preferably made of Si having a <110> crystal orientation. In this case, in the anisotropic etching step described above, it is preferable to perform anisotropic etching by wet etching using a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, or a TMAH aqueous solution.

  According to the 3rd aspect of this invention, the manufacturing method of the porous resin body which can manufacture the porous resin body in which many holes were formed at low cost is provided. According to this method, the resin material is heated to a temperature near the glass transition point, and the above-described porous body is pressed against the heated resin material. Thereby, the hole pattern of the porous body is transferred to the resin material to obtain a porous resin body in which a large number of holes are formed.

  In the nanoimprint technology with excellent mass production cost, the mold (stamper) is expensive, but according to the above-mentioned method, the stamper (porous body) can be manufactured at low cost. The resin body can be manufactured at a very low cost.

  According to the 4th aspect of this invention, the manufacturing method of the porous resin body which can manufacture the porous resin body in which many holes were formed at low cost is provided. According to this method, the resin material is heated to a temperature in the vicinity of the glass transition point, and the heated resin material having fluidity is poured into the pores of the porous body described above. The resin material poured into the pores of the porous body is cooled and cured, and the porous body is removed from the resin material. Thereby, a porous resin body in which a large number of holes are formed is obtained.

  According to this method, a mold (porous body) having very fine straight holes can be manufactured at low cost, and can be repeatedly used as a mold. Therefore, a porous resin having very fine straight holes The body can be mass-produced at low cost.

  According to the 5th aspect of this invention, the manufacturing method of the porous resin body which can manufacture the porous resin body in which many holes were formed at low cost is provided. According to this method, the resin material dissolved in the solvent is poured into the pores of the porous body described above. The resin material poured into the pores of the porous body is heated to volatilize the solvent, and the porous body is removed from the resin material. Thereby, a porous resin body in which a large number of holes are formed is obtained. In this case, after evaporating the solvent, the resin material may be cured by irradiating the resin material with ultraviolet rays.

  ADVANTAGE OF THE INVENTION According to this invention, the porous body and porous resin body in which many holes were formed can be manufactured at low cost.

  Hereinafter, embodiments of a method for producing a porous body and a method for producing a porous resin body according to the present invention will be described in detail with reference to FIG. 1 (a) to FIG. 7 (c). In FIG. 1A to FIG. 7C, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  A method for producing a porous body according to the first embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (d). First, as shown in FIG. 1A, a base material 1 made of Si having a <110> crystal orientation is prepared. It is preferable that the film thickness of this base material 1 is 5 micrometers-1 mm, for example. Then, as shown in FIG. 1B, for example, Cu is formed on the surface 1a of the base material 1 by sputtering for an extremely short time to form an irregular discontinuous film 2.

  FIG. 2A to FIG. 2C are schematic views showing the growth process of such a discontinuous film 2. In the initial stage of film formation, an island-like discontinuous film 2a is formed on the surface 1a of the substrate 1 as shown in FIG. As the film formation continues, the island-like discontinuous films 2a gradually grow larger and the adjacent discontinuous films 2a are connected to each other. Eventually, as shown in FIG. 2B, as a whole, the discontinuous film 2b having the holes 3 formed therein is formed. When the film formation is further continued, the above-described hole 3 is also filled and becomes a continuous film 4 as shown in FIG. 2C, but in this embodiment, an island-like discontinuous film 2a as shown in FIG. Alternatively, a discontinuous film 2b in which holes 3 are formed in places as shown in FIG.

  After the discontinuous film 2 (2a or 2b) is formed on the surface 1a of the base material 1 as described above, as shown in FIG. 1C, the surface 1a of the base material 1 using the discontinuous film 2 as a mask. Is anisotropically etched. Thereby, only the part not covered with the discontinuous film 2 is etched, and the through-hole 5 is formed in the base material 1. Thereafter, as shown in FIG. 1 (d), the discontinuous film 2 used as a mask is removed if necessary, followed by washing with pure water and drying. Thereby, the porous body 6 in which many through-holes 5 were formed can be obtained.

  The anisotropic etching described above can be performed by wet etching using an etching solution such as a sodium hydroxide (NaOH) aqueous solution, a potassium hydroxide (KOH) aqueous solution, or a TMAH aqueous solution. In this case, as the material of the discontinuous film 2 serving as a mask, a material that is not affected by alkali or is not easily affected by alkali must be selected. As such a material, in addition to the above-described Cu, Ru, Co, Metal materials such as Ta, Ti, W, Fe, Ni, Au, Ag, Pb, TaN, TiN, WN, and WNC, and resin materials such as polyethylene, fluororesin, and polyimide can be used. As a method for forming the discontinuous film 2 with a metal material, CVD or vapor deposition can be used in addition to the above-described sputtering.

  Further, after the discontinuous film 2 made of such a metal material is formed, the discontinuous film 2 may be subjected to annealing treatment or laser irradiation treatment as necessary. By such annealing treatment or laser irradiation treatment, impurities in the discontinuous film 2 are released and the film quality is improved, and the island-like discontinuous film 2a (see FIG. 2A) is formed in various places. There is an effect that the shapes of the holes 3 (see FIG. 2B) are aligned.

  Here, when the substrate 1 made of Si having a crystal orientation of <110> is used, anisotropic etching with a very high aspect ratio can be performed. Therefore, the porous body 6 having the through holes 5 having a very high aspect ratio can be manufactured at a low cost. Further, when the substrate 1 made of Si is used, an existing semiconductor manufacturing apparatus can be used in steps such as the formation of the discontinuous film 2, annealing treatment, laser treatment, and anisotropic etching treatment.

  Moreover, if Si having a crystal orientation of <110> is used as the base material 1 and wet etching is performed using an alkaline aqueous solution such as a sodium hydroxide aqueous solution (NaOH), a potassium hydroxide (KOH) aqueous solution, or a TMAH aqueous solution, In addition, highly anisotropic etching can be performed. By such anisotropic etching, only the portion where the discontinuous film 2 does not exist can be etched vertically and dug down. For example, when KOH is used as the etching solution, the ratio of the etching rate between the <110> plane and the <111> plane perpendicular thereto, that is, the etching rate in the depth direction perpendicular to the surface 1a of the substrate 1 and the substrate 1 The ratio of the etching rates in the direction parallel to the surface 1a is about 180: 1, and anisotropic etching with a very high aspect ratio can be performed. Since NaOH and KOH are easily available and inexpensive, they are easy to use as the above-described etching solution. For example, a discontinuous film 2 made of Ta is formed by sputtering on the surface of a <110> oriented Si substrate, and the surface of the Si substrate with the Ta discontinuous film is immersed in a 40% KOH aqueous solution at 40 ° C. Etching can be performed.

  In addition, when TMAH is used as an etching solution, TMAH is an organic alkali that does not contain metal ions, so there is no concern about metal contamination, and it is advantageous for the production of a porous body used for semiconductor processes that do not like metal contamination. It is.

  When the discontinuous film 2 is formed of a resin material, for example, a fine powder of the resin material may be spread on the surface 1a of the base material 1 and the resin material may be heated and adhered together with the base material 1. As an etching method in this case, a method such as wet etching or dry etching can be selected according to the material of the substrate 1.

  1C and FIG. 1D, an example in which the hole 5 is penetrated through the base material 1 by anisotropic etching has been described, but as shown in FIG. 3A and FIG. 3B. In addition, the anisotropic etching is finished before the hole penetrates the substrate 1, and the porous body 6a having the hole 5a opened on only one side can be formed. When the island-like discontinuous film 2a (see FIG. 2A) is used as a mask, the base material 1 is prevented from falling apart by stopping the anisotropic etching halfway in this way. be able to.

  According to the method of the present embodiment, the porous body 6 having fine straight holes 5 can be manufactured at low cost by anisotropically etching the base material 1 using the discontinuous film 2 that can be formed at low cost as a mask. it can. In other words, it is possible to inexpensively form masks corresponding to a wide range of pore sizes ranging from relatively large pore sizes on the micron order and beyond to extremely fine pore sizes on the nano order. A porous body having pores can be produced at low cost.

  A method for producing a porous body according to the second embodiment of the present invention will be described with reference to FIGS. 4 (a) to 4 (d). First, as shown in FIG. 4A, for example, a base material 1 made of Si having a crystal orientation of <110> is prepared. Then, as shown in FIG. 4B, a porous material 8 having irregular open cells 7 such as a porous polyethylene sintered body is formed on the surface 1a of the substrate 1. As a method for forming such a porous material 8 on the surface 1a of the substrate 1, for example, a phase separation method, a sintering method, an anodizing method, or the like can be used. Moreover, as a material of the porous material 8, polyethylene, polyimide, alumina, titanium oxide, SiC, or the like can be used.

  And as shown in FIG.4 (c), the surface 1a of the base material 1 is anisotropically etched using this porous material 8 as a mask. That is, the surface 1 a of the base material 1 that is in close contact with a portion other than the open cells 7 of the porous material 8 is etched, and only the surface 1 a of the base material 1 that is in contact with the open cells 7 is etched. Thus, only the surface 1a of the base material 1 in contact with the open cells 7 of the porous material 8 is etched to form the through holes 5 in the base material. Similar to the first embodiment, this anisotropic etching can be performed by wet etching using an etching solution such as a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, or a TMAH aqueous solution.

  Then, as shown in FIG.4 (d), the porous material 8 is removed as needed, and pure water washing | cleaning and drying are carried out. Thereby, the porous body 6 in which many through-holes 5 were formed can be obtained. 4 (c) and 4 (d), an example in which the hole 5 is penetrated through the base material 1 by anisotropic etching has been described, but as shown in FIGS. 5 (a) and 5 (b). In addition, the anisotropic etching is finished before the hole penetrates the substrate 1, and the porous body 6a having the hole 5a opened on only one side can be formed.

  As a manufacturing method of the porous material 8 used in the present embodiment, various methods and materials have been conventionally considered, and there are very various options. Therefore, according to the present embodiment, the optimum porous material 8 can be selected from a variety of options and used as a mask according to various demands such as the base material 1, the anisotropic etching method, and the desired pore size. it can. As described above, according to the present embodiment, the production cost of the mask is reduced, and further, the material and pore size of the mask can be selected from various options, and the porous material has fine through-holes with a wide pore size. The body can be manufactured at low cost.

  FIG. 6A to FIG. 6C are schematic views for explaining a method for producing a porous resin body using the porous body produced by the above-described method. First, the resin material 10 is prepared and heated to near the glass transition point. As this resin material 10, for example, polycarbonate resin or acrylic resin can be used. Then, as shown in FIG. 6A, the porous body 20 manufactured by the above-described method is prepared as a nanoimprint technique mold (stamper).

  Then, as shown in FIG. 6B, the porous body 20 is pressed against the heated resin material 10, and a negative pattern (inverted pattern) corresponding to the numerous holes 21 formed in the porous body 20 is resind. Transfer to material 10. As shown in FIG. 6C, when the porous body 20 as a stamper is lifted, a porous resin body 12 having a large number of holes 11 is obtained.

  In the nanoimprint technology with excellent mass production cost, the stamper is only expensive. However, according to the method described above, the stamper can be manufactured at low cost. It can be carried out.

  Fig.7 (a) to FIG.7 (c) is a schematic diagram for demonstrating the other method of manufacturing a porous resin body using the porous body manufactured by the method mentioned above. In this example, the porous body 30 manufactured by the above-described method is used as a mold for injection molding. First, as shown in FIG. 7A, a porous body 30 manufactured by the above-described method is prepared. As shown in FIG. 7B, a large number of holes 31 formed in the porous body 30 are formed. Then, the resin material 40 having a fluidity is poured by being heated to near the glass transition point. Then, the resin material 40 poured into the holes 31 of the multilayer body 30 is cooled and cured. Thereafter, as shown in FIG. 7C, the porous body 30 is formed by removing the porous body 30 from the resin material 40 (mold release), thereby obtaining a porous resin body 42 in which a large number of holes 41 are formed.

  In this method as well, as in the example of the nanoimprint technique described above, a mold having very fine straight holes can be manufactured at low cost and used repeatedly as a mold. The porous resin body can be mass-produced at low cost.

  Further, a resin material dissolved in a solvent is poured into the pores of the porous body 30 described above, and the resin material is heated to volatilize the solvent, and then the porous body 30 is removed (released) from the resin material. A quality resin body may be formed. In this case, after volatilizing the solvent, it is preferable to cure the resin material by irradiating the resin material with ultraviolet rays.

  Thus, if a porous resin body is formed by a nanoimprint technique or an injection molding technique using the porous body manufactured by the above-described method, a porous resin body having straight holes can be manufactured at low cost.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention may be implemented in various forms within the scope of the technical idea.

Fig.1 (a) to FIG.1 (d) is a schematic diagram for demonstrating the manufacturing method of the porous body in the 1st Embodiment of this invention. FIG. 2A to FIG. 2C are schematic diagrams for explaining the process of forming the discontinuous film shown in FIG. FIG. 3A and FIG. 3B are schematic views for explaining a modification of the method for producing a porous body in the first embodiment of the present invention. FIG. 4A to FIG. 4D are schematic views for explaining a method for manufacturing a porous body in the second embodiment of the present invention. Fig.5 (a) and FIG.5 (b) are the schematic diagrams for demonstrating the modification of the manufacturing method of the porous body in the 2nd Embodiment of this invention. FIG. 6A to FIG. 6C are schematic views for explaining a method for producing a porous resin using the porous body according to the present invention. Fig.7 (a) to FIG.7 (c) is a schematic diagram for demonstrating the method to manufacture porous resin using the porous body which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Discontinuous film 5 Hole 6 Porous body 7 Open cell 8 Porous material 10,40 Resin material 11,41 Hole 12,42 Porous resin body 20,30 Porous body 21,31 Hole

Claims (17)

A discontinuous film forming step of forming a discontinuous film on the surface of the substrate;
An anisotropic etching step of anisotropically etching the surface of the base material using the discontinuous film as a mask to obtain a porous body in which a large number of holes are formed;
A method for producing a porous body, comprising:   The method for producing a porous body according to claim 1, wherein the discontinuous film forming step forms an irregular discontinuous film.   The method for producing a porous body according to claim 1, further comprising a discontinuous film removing step of removing the discontinuous film used as the mask.   The said discontinuous film formation process forms the said discontinuous film by sputtering, CVD, or vapor deposition, The manufacturing method of the porous body as described in any one of Claim 1 to 3 characterized by the above-mentioned.   The method for producing a porous body according to claim 4, further comprising a step of performing an annealing process or a laser irradiation process on the discontinuous film after the discontinuous film forming step.   The discontinuous film forming step includes a discontinuous film made of Cu, Ru, Co, Ta, Ti, W, Fe, Ni, Au, Ag, Pb, TaN, TiN, WN, WNC, polyethylene, fluororesin, or polyimide. The method for producing a porous body according to any one of claims 1 to 5, wherein: is formed. A porous material forming step of forming a porous material having continuous pores on the surface of the substrate;
An anisotropic etching step of anisotropically etching the surface of the base material using the porous material as a mask to obtain a porous body in which a large number of holes are formed;
A method for producing a porous body, comprising:   The method for producing a porous body according to claim 7, wherein the porous material forming step forms a porous material having irregular continuous pores.   The method for producing a porous body according to claim 7 or 8, further comprising a porous material removing step of removing the porous material used as the mask.   The porous material forming step of forming the porous material according to any one of claims 7 to 9, wherein the porous material is formed by a phase separation method, a sintering method, or an anodizing method. Production method.   The said porous material formation process forms the porous material which consists of polyethylene, a polyimide, an alumina, a titanium oxide, or SiC, The manufacturing of the porous body as described in any one of Claim 7 to 10 characterized by the above-mentioned. Method.   The method for producing a porous body according to any one of claims 1 to 11, wherein the base material is made of Si having a crystal orientation of <110>.   The method for producing a porous body according to claim 12, wherein in the anisotropic etching step, anisotropic etching is performed by wet etching using an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, or an aqueous solution of TMAH. Heat the resin material to a temperature near the glass transition point,
A porous body manufactured by the method according to any one of claims 1 to 13 is pressed against the heated resin material, and a pattern of pores of the porous body is transferred to the resin material. A method for producing a porous resin body, comprising: obtaining a porous resin body having pores formed therein. Heat the resin material to a temperature near the glass transition point,
The heated resin material having fluidity is poured into the pores of the porous body produced by the method according to any one of claims 1 to 13,
Cooling and curing the resin material poured into the pores of the porous body,
A method for producing a porous resin body comprising removing the porous body from the resin material to obtain a porous resin body in which a large number of pores are formed. A resin material dissolved in a solvent is poured into the pores of the porous body produced by the method according to any one of claims 1 to 13,
Heating the resin material poured into the pores of the porous body to volatilize the solvent,
A method for producing a porous resin body comprising removing the porous body from the resin material to obtain a porous resin body in which a large number of pores are formed.   The method for producing a porous resin body according to claim 16, wherein after the solvent is volatilized, the resin material is cured by irradiating the resin material with ultraviolet rays.

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